1. Technical Field
The present invention relates to a semiconductor element drive device which, as well as driving a semiconductor element configuring, for example, a power converter, has a function of identifying a protection operation.
2. Related Art
As this kind of semiconductor element drive device, for example, an alarm circuit described in JP-A-08-70580 is known. In this heretofore known example described in JP-A-08-70580, an intelligent power module (IPM), which is a power transistor module driving an inverter, includes an overcurrent alarm unit, an overvoltage alarm unit, and an overheat alarm unit.
In the heretofore known example described in JP-A-08-70580, the overcurrent alarm unit is configured to output a first alarm signal having a first pulse width when detecting an overcurrent condition of a power transistor. Also, the overvoltage alarm unit is configured to detect an overvoltage condition of an output terminal of the power transistor and output a second alarm signal having a second pulse width. Furthermore, the overheat alarm unit is configured to detect an overheat condition of the power transistor and output a third alarm signal having a third pulse width. For this reason, simply by detecting the pulse width of the output alarm signal, it is possible to easily determine whether the power transistor is in the overcurrent condition, overvoltage condition, or overheat condition.
Also, as another semiconductor element drive device, an intelligent power module shown in JP-A-2002-27665 is proposed. In this heretofore known example described in JP-A-2002-27665, the intelligent power module includes a required number of semiconductor switching elements, a drive circuit, and various kinds of detection circuit and warning circuit which detect a fatal anomaly and precursory anomaly of the switching elements, drive circuit, or the like. Also, in the heretofore known example described in JP-A-2002-27665, the intelligent power module includes an anomaly detection logic which carries out a switching element protection operation at a time of the anomaly detection by the detection circuits and warning circuits, a control circuit for outputting a signal based on an anomaly detection signal to the exterior, and a transmission circuit.
In the heretofore known example described in JPA-2002-27665, an output terminal from which an alarm signal is output when detecting the fatal anomaly, and an output terminal from which is output an anomaly factor identification signal indicating an anomaly factor including the fatal anomaly and precursory anomaly, are provided in the transmission circuit, and preferably, a configuration is such as to share them as a single output terminal.
Furthermore, as another semiconductor element drive device, an intelligent power module described in JPA-2000-341960 is proposed. In this heretofore known example described in JP-A-2000-341960, the intelligent power module includes IGBT's configuring a power conversion bridge circuit of an inverter, a semiconductor device integrally housing an IGBT 1DB, which interrupts a current consuming the generative power of a motor via a resistor, and a predriver incorporating a drive circuit and protection circuit of a corresponding IGBT. Then, the protection circuit, when there is an anomaly, outputs an alarm ALM1 to the exterior of the intelligent power module via an alarm enable line. However, the protection circuit determines that there is a sign of an occurrence of an anomaly, at a point at which a collector current of an IGBT or a chip temperature is higher than when normal and exceeds a predetermined value lower than a level when issuing the alarm ALM1, before outputting the alarm ALM1. A configuration is such that, when it is determined that there is a sign of an occurrence of an anomaly, an advance alarm ALM2 is output to the exterior of the intelligent power module via an advance alarm line without the IGBT being cut off.
Also, a semiconductor element drive circuit described in JP-A-2007-324828 is proposed. In this heretofore known example described in JP-A-2007-324828, the semiconductor element drive circuit includes a command unit which generates a control signal of an IGBT, a gate circuit which controls the IGBT, and a monitoring circuit which monitors the principal current or collector voltage of the IGBT. Then, a configuration is such that a protection circuit controls the gate circuit when an output from the monitoring circuit exceeds a predetermined value, and notifies the command unit of an anomaly, a count circuit receives the anomaly notification from the protection circuit, and counts the number of anomaly notifications, and the command unit, when the number of counts is at least two or more, determines that an anomaly has occurred.
Furthermore, an electric motor drive control device described in JP-A-2007-82360 is proposed. In this heretofore known example described in JP-A-2007-82360, the electric motor drive control device includes a main circuit which converts direct current power to alternating current power and drives an electric motor which is a load, a driver circuit which drives a power semiconductor switching element of the main circuit, and a host controller which sends a drive signal to the driver circuit. Then, the driver circuit includes an anomaly sensing circuit and an anomaly information PWM converter which sends a PWM pulse with a duty corresponding to the kind of a sensed anomaly to the host controller as anomaly information.
However, in the heretofore known example described in JP-A-08-70580, the intelligent power module individually detects an overcurrent anomaly, overvoltage anomaly and overheat anomaly of the power transistor configuring the inverter, and outputs first to third alarm signals with differing pulse widths to the exterior. Then, by detecting the pulse width of each alarm signal, it is possible to detect which one of the overcurrent anomaly, overvoltage anomaly, and overheat anomaly an anomaly is. However, in the heretofore known example described in JP-A-08-70580, an overcurrent alarm unit, overvoltage alarm unit, and overheat alarm unit, when detecting the overcurrent anomaly, overvoltage anomaly, and overheat anomaly respectively, function as a one-shot multivibrator, and output one alarm signal with a predetermined pulse width. For this reason, there is an unsolved problem in that, when an alarm signal is output from another alarm unit before the alarm signals are returned simultaneously, or one alarm signal is returned, to an on condition by the plural alarm units, the alarm signal is falsely detected.
Also, in the heretofore known example described in JP-A-2002-27665, there is an unsolved problem in that it is necessary to output two kinds of signal, an alarm signal and an anomaly factor identification signal, resulting in a complicated configuration of a signal formation circuit.
Furthermore, in the heretofore known example described in JP-A-2000-341960, the protection circuit, when there is an anomaly, outputs the alarm ALM1 to the exterior via the alarm enable line. Also, the protection circuit determines that there is a sign of an occurrence of an anomaly, at a point at which the collector current of the IGBT or the chip temperature is higher than when normal and exceeds a predetermined value lower than the level when issuing the alarm ALM1, before outputting the alarm ALM1. Then, a configuration is such that, when it is determined that there is a sign of an occurrence of an anomaly, the IGBT outputs the advance alarm ALM2 to the exterior via the advance alarm line. However, in the heretofore known example described in JP-A-2000-341960, there is an unsolved problem in that, it not being possible to identify the collector current or chip temperature, it is only possible to determine whether there is a condition in which an anomaly has occurred or there is a sign of the anomaly occurrence before that, and it is not possible to identify an anomalous condition.
Also, in the heretofore known example described in JP-A-2007-324828, a configuration is such that, in order to prevent the inverter being stopped by a false signal from the protection circuit, the command unit determines that there is an anomaly when the number of counts, wherein the number of anomaly notifications received from the protection circuit is counted, is two or more, but there is an unsolved problem in that it is not possible to simply identify an anomalous condition.
Furthermore, in the heretofore known example described in JP-A-2007-82360, a configuration is such that a PWM pulse with a duty corresponding to the kind of a sensed anomaly is sent to the host controller as anomaly information, and the pulse width is changed depending on the kind of the sensed anomaly. However, as well as it being difficult to accurately determine the kind of the anomaly with the size of the duty, the PWM pulse is output while the anomaly is continuing, meaning that when the duty ratio becomes higher, the interval between adjacent pulses becomes narrower. For this reason, in the heretofore known example described in JP-A-2007-82360, as a total time of the repeatedly output PWM pulses is measured, there is an unsolved problem in that an error is liable to occur in the measurement of the alarm time, and it is difficult to accurately determine the kind of an anomaly.